Imperfections or Defects in crystalline solids

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 Imperfections or Defects in crystalline solids :

In an ionic crystal the particles are well orderly arranged in a regular pattern. An ideal crystal is that which has same until cell containing the same lattice points through out the whole crystal. But, such ideal crystal only exists at zero Kelvin temperature i.e., entropy of it's particle is zero. It means that there is no movement of the constituent particles at 0K. But, none of the crystals are basically ideal and it suffers certain defect at temperature above 0K. This defect may arise due to some irregularities in the arrangement of constituent particles in the crystal lattice and are called imperfections or crystal defects. These are of two types.

Point defects:

                These defect are due the irregularities in the arrangement of atoms around a point or an atom in a crystalline solid. These are also called atomic defects.


Line defects: 

                 These defects are due to the irregularities in the arrangement of entire rows of lattice points.


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